diff --git a/FFMpegCore.Test/ArgumentBuilderTest.cs b/FFMpegCore.Test/ArgumentBuilderTest.cs
index 71bc90b..6fd108d 100644
--- a/FFMpegCore.Test/ArgumentBuilderTest.cs
+++ b/FFMpegCore.Test/ArgumentBuilderTest.cs
@@ -334,7 +334,7 @@ public void Builder_BuildString_SubtitleHardBurnFilter()
                                 .WithParameter("PrimaryColour", "&HAA00FF00")))))
                 .Arguments;
 
-            Assert.AreEqual("-i \"input.mp4\" -vf \"subtitles=sample.srt:charenc=UTF-8:original_size=1366x768:si=0:force_style='FontName=DejaVu Serif\\,PrimaryColour=&HAA00FF00'\" \"output.mp4\"",
+            Assert.AreEqual("-i \"input.mp4\" -vf \"subtitles=sample.srt:charenc=UTF-8:original_size=1366x768:stream_index=0:force_style='FontName=DejaVu Serif\\,PrimaryColour=&HAA00FF00'\" \"output.mp4\"",
                 str);
         }
 
diff --git a/FFMpegCore/FFMpeg/Arguments/SubtitleHardBurnArgument.cs b/FFMpegCore/FFMpeg/Arguments/SubtitleHardBurnArgument.cs
index 1186ae2..a48f845 100644
--- a/FFMpegCore/FFMpeg/Arguments/SubtitleHardBurnArgument.cs
+++ b/FFMpegCore/FFMpeg/Arguments/SubtitleHardBurnArgument.cs
@@ -74,7 +74,7 @@ public SubtitleHardBurnOptions SetOriginalSize(Size size)
         /// </remarks>
         public SubtitleHardBurnOptions SetSubtitleIndex(int index)
         {
-            return WithParameter("si", index.ToString());
+            return WithParameter("stream_index", index.ToString());
         }
 
         /// <summary>